Fuel oil preheat control



Sept. 6, 1949.

c. L. RAYFIELD 2,481,038

FUEL OIL PREHEAT CONTROL Filed April 3, 1946 2 Sheets-Sheet 1 O 7 i M y ww M35 5.

C. L. RAYFIELD FUEL on. PREHEAT CONTROL Sept. 6, 1949.

2 Sheets-Sheet 2 Filed April 3, 1946 Patented Sept. 6, 1949 FUEL OIL PREHEAT CONTROL Charles L. Rayfield, Chicago, Ill., assignor to C. L. Rayfield Company, Chicago, 111., a corporation of Illinois Application April 3, 1946, Serial No. 659,382

2 Claims. r 1 The present invention relates to improvements in maintaining close temperature control of a contained liquid, such as for example fuel oil.

The present invention is herein shown and described as'having to do with a fuel oil preheat control .of fuel for an oil burner and has to do with means for preventing starting of the blower or compressor until the temperatlue of the fuel oil has been preheated to its ignition value.

In the oil burner field there are many burners utilizing as fuel, oils of more or less volatile characteristics. Where the fuel oil is of less volatile character, for example, No. 5, it has been found that on starting an oil burner using such fuel, much liquid fuel is lost before the temperature of the oil is raised to its ignition point. Such excess oil is driven into-the boiler or heater furnace by the blower and then when ignition does take place causes objectionable smoke. Furthermore the waste of such oil is uneconomical, and delayed ignition is a source of danger and possible explosion.

It is therefore an object of the present invention to provide in a fuel oil burning system means for preventing discharge of fuel oil into the furnace until the temperature thereof has been raised to its ignition value.

Another object of the present invention is to provide a fuel oil burning system adapted for burning a less volatile fuel oil, such for example, as No. 5.

A further object of the present invention is to provide in a fuel oil burning system means for preheating the oil, prior to its delivery into a furnace, to raise its temperature to its ignition value.

Another and still further object of the present invention is to provide, in a fuel oil burning system, means for preheating the oil prior to its delivery into a furnace, and means operable when the temperature of the oil reaches its ignition value for enabling operation of the burner by the room thermostat which controls the burner motor and oil ignition means responsive to temperature differentials in the room or space to be heated.

The invention has for a further object the provision, in a fuel oil burning system, of an oil preheater so that any burnable fuel oil may be used regardless of its volatility.

Another and yet further object of the present invention is to provide an immersed heater for any purpose where any liquid is used in a tank or other confined space, together with means for breaking a heating circuit when the liquid temperature reaches a predetermined value.

The invention has for an additional object the provision, in a fuel oil burning system, of an immersion type preheater for preheating the oil prior to its admission to the nozzle, and utilizing a bimetal member responsive to the temperature of the oil in the burner for closing a relay or solenoid circuit, which circuit in turn readies the circuit between the burner and room thermostat to actuate the burner when the thermostat calls for heat.

Another object of the present invention is to provide simple control means, in connection with a preheater for fuel oil of an oil burning system, which is eiiicient in use, of simple construction, and positive in action.

Another object of the present invention is to provide an immersion type thermostatic control, for use in fuel oil burner systems, which control is immersed in the fuel oil in a suitable container and which control holds .open the electrical circuit between the room thermostat and burner motor until the temperature of the fuel oil has been raised to its ignition value whereupon the circuit is readied so that it may be closed when the thermostat calls for heat.

An important object of the invention is to prevent starting the oil burner until the oil is heated to its ignition value.

Generally speaking the control of the present invention utilizes a bimetal element supported on the preheater which is immersed in the oil, and which bimetal element, as the oil temperature rises to its ignition value, actuates a lever which when moved in one direction by the bimetal element opens the heater circuit and closes a quick make and break switch with snap action to ready the circuit between the thermostat and the burner motor. Such bimetal element is not affected by the sulfur in the oil, has no charge to lose, will continue in service for a long period of time without replacement or repair, and is capable .of ready adjustment so that the system may be adapted to the ignition point of the particular fuel oil being used. The bimetal element moves in the opposite direction when the temperature of the oil drops.

The above, other and further objects of the present invention will be apparent from the following description and accompanying drawings.

The accompanying drawings, somewhat schematic in character, illustrate an embodiment of the present invention and the views thereof are as Qll9ws:'

' shown in Figures 2 'and '3 Figure l is a fragmental sectional view of a burner oil container, showing the preheater, the bimetal element, and related parts for operating a switch when the temperature of fuel oil in the oil container rises to a predetermined value;

Figure 2 is a view similar to Figure 1, looking at the lefthand of Figure 1, and showing the relationship of. parts ;-When the temperature. of the oil is below its predetermined value; and

Figure 3 is a wiring diagram showing the manner of connecting the control of the present invention in circuit with the burner motor and stack relay.

Referring to the drawingsl i the bottom of the oil container, and B designates one of the walls of the container. An electrically operated preheater P is supported-on'thebottom 5 and has external posts 1 and 8 whereby-the preheater may be connected in an electric circuit. Partially surrounding .the preheater P is, a bi.- metal element B having a free end portion 9. The element B .is secured to. thepreheater P by .a strap surroundingthe preheater and overlying a widened portion II of the bimetal element B. The ends of. the strap ill are connected by a bolt [2 as shown in the drawings.

Supported on the exterior oi the wall, 6 is an insulating plat'e. l3 spaced from the adjacent wall 6, on which is mounted a micro switch S which is a one-pole two-throw switch. The switch is encased in a suitable box. 4

Projecting hrough a side of he Q i p Projecting through the Wallfi is a rocker arm l5 carried by a bushing .15 inserted through an aperture in the wall 6 an secured in place by a nut I1 engaging the threade d surface of. the bushing. Enteredpthrough. a suitable aperture in the inner end of, the rocker arm l5 is a lever The motor M has terminals 35 and 36 while the ignition transformer IG has terminals 31 and 38.

39 designates generally the burner panel box and 40 designates the stack relay which controls the operation of the fuel oil burner in accordance with. temperature differentials in the room or space to be heated. 5 7- Mounted on a suitable insulating block in the panel box 39 are binding posts 4|, 42, 43, 44, 45, 46, 41, 48, 49, and 50. The posts 43, 44 and 46 are connected by a bus bar 5|. The posts 41, 48, 49 and 5!] are connected by a bus bar 52, the bus bars being, arranged'as illustrated in Figure 3.

18 having an annularly displaced end 9 disposed in the pathof 1 movement of the free end 9 of the bimetalelementlia. r p

Mounted on theouter end ofthe rocker arm I5 is a crank arm 20,.il1ustrated ashaving one end split asv at 2| to encompass the, outer endof the rocker arm 15, the split ends being .drawn tight by a bolt 22. Ifdesired a screw23 may be threaded into the-outer. endof the rocker arm I5 providing additional ,securement oi. the crank 20 to the rocker arm l5 Thelower endof the crank 20, as shownlathe drawings swings responsively to swingingmovement. imparted to the lever 18 bythefree, end 1%!.,0f ,tli1e,birnetal element B. Thecrank 20 'isfilQYidedwith ascrew 24 having a1head .'2 4 d, adapted to engage the pin l4 when the cranhmis given clockwise movement, asviewed in Figures 2 and 3, by the swing of the lever l3.

The micro switch S jmdiiitdpat e plate 13.

by screws 25 while the plate is secured to the wall Referring to Figurefi it will be noted that the micro switch S includes a springcontact finger 2T fastened atone end in iixedrelation 1. 0 the base of the switch, and in electrical association with a binding post The free end or the finger 21 ismovablejbetween contacts and 3].

The finger 21 is a spring arm and so stressedthat normally the contact endfilis in engagement in of. the p'in l4 to-maintain the pin projected as M des ate ,.eenerallg the 'liiiotor of the circuit, closing relation with the c o r 1tact1H1. The a finger 2.1 carries a hump 331engaging thehead 3.4

burner and IG designates the ignition trans- 1 former.

Line wires 53 and 54 communicate with a source of electrical supply and a line switch, not shown, is-inserted to connect and disconnect the wires 53 and 54 with the supply as occasion may demand, i c The line wire 53 is connectedto the binding post 45 of the panel box. The line wire 5 3 may be termed the hot wirewhile the wire 54 may be termed the ground wire. 1 w p The ground wire .54 is. connected to a terminal 55 in the stack relay 40. A conductor 56 connects .the terminal 55 with thebinding post. 50 in the panel box 39. Acontact 5 1 in thestack relay .40 is connected by. a conductor 58 to the binding post 43 in the panel box. The motor terminal is connected by a conductor 59 tothe binding post M in the panel box... The terminal 36 of the motor is connected by a conductor 6 0 to theterminal 41 in the panel box. The terminal 31 of the ignition transformer is connected bya conductor 6| to the. binding. post 42, while the terminal 38 of the transformeris connected by a conductor 62 to the binding post 49 of the box.

In the stack relay is a motor terminal or contact 63 connected by conductor 64 to the binding post 4| in the panelbox. An ignition terminal 35 in the stack relay 4 0 is connected by a conductor 66 tothe binding post 42.

A conductor 61 connects the terminal post 29 of the micro switch S to the binding post 45. A conductor 68 connects the terminal 8 of the preheater P to the binding post 50. A conductor 69 connects the terminals, 1 of the preheater P with a contact 30 of the micro switch. A conductor 1c connects the contact 3] of the ,micro switch with terminal 46 in the panel box 39, v

Within the panel box 39, and pivoted at H to swing is a lever '12 carrying at one end a mercury switch 13, the mercury switch being secured to the lever'l2 by a strap or other suitable fastening M. A solenoid 15 is supported by the panel box 39 and is so disposed that its armature 16 underlies an end of the lever". The winding of the solenoid is connected 'by one conductor 17 to binding post 4| and by another conductor 18 to binding post 50. a

. Referring tothe mercury switch 13 a conductor 19 connects one of the contact points of the switch with binding post 44 while 'a conductor 80. connects the other binding .post or contact of the mercury switch with the. vbindingpost 45.

When the heat is ofi, and the burner and motor not running, the lever 12 is in theipositionsh'own byfull lines in Figure 3 to open the circuit be- The mercury'switch, in Figure 3, is shownin circuit open position, in full lines, and in circuit closing position in dotted lines.

Let us suppose that the time has arrived to require heat. The line switch is closed, the closing of which completes a circuit through the preheater P as follows:

Line 53, binding post 45, conductor 61, contact 29 of the micro switch, spring finger 21, contact 30 of the micro switch, conductor 69 to terminal post 1 of the preheater, through the preheater, thence from the binding post 8 through conductor 68 to binding post 50 of the ground. This circuit energizes the preheater which raises the temperature of the oil in the crank case or base of the burner.

With the circuit to the mercury switch open, even though the stack relay 40 calls for heat, the motor will not operate unless and until the solenoid I5 is energized to tilt the mercury switch 13 in a manner to close its contacts.

As the temperature in the crank case rises the free end 9 of the bimetal member moves to the left, as viewed in Figure 3, which will eventually cause the pin l4 to swing the spring contact 21 away from the terminal 30 and against the terminal 3|. With the spring finger 21 against the terminal 3| the solenoid 15 is energized by a circuit as follows:

Line conductor 53, binding post 45, conductor 61, contact 29 of the micro switch, spring finger 21, terminal 3|, conductor It, binding post 46, bus bar 5| to post 43, thence by conductor 58 to contact 51, through stack relay 4!! to contact 63, thence by conductor 64 to binding post 4|, thence by conductor 11 to solenoid and by conductor 18 to post 50 of the ground. Completion of this circuit energizes the solenoid to cause its armature 16 to tilt the lever 12 in a manner to close circuit through the mercury switch 13.

Suppose after the mercury switch has been closed, the thermostat calls for heat, which energizes the stack relay 40, a circuit is established as follows:

Conductor 53, binding post 45, conductor 80, through the mercury switch '13, out through the conductor 19, the binding post 44, binding post 43, conductor 58, to contact 51 of the stack relay. The thermostat having called for heat, there will be a connection between the contact 51 and the contact 63 of the stack relay, thus completing the circuit through conductor E4, binding post 4 I, conductor 59, contact 35 of the motor, through the motor, out through the contact 36, thence by conductor 60 to binding post 4? of the ground. This circuit operates the burner as long as the thermostat calls for heat and as long as the mercury switch is in circuit closing position.

After the solenoid 15 has been energized by the bimetal circuit, to close a circuit through the mercury switch 13, the solenoid is maintained energized by a circuit as follows:

Conductor 53, binding post 45, conductor 80, mercury switch 13, conductor 19, binding post 44, binding post 43, conductor 58, contact 51, contact 63, conductor 64 to post 4|, thence by conductor 11 through solenoid and by conductor 18 to the binding post 50 of the ground. Thus the solenoid will remain energized as long as the mercury switch is in circuit closing position, and the thermostat calls for heat.

When the thermostat calls for heat a circuit through the transformer IG is established as follows:

Conductor 53, binding post 45, conductor 80, mercury switch 13, conductor 19, binding post 44,

binding post 43, conductor 58, to contact 51 of the stack relay, thence to contact 65 of the stack relay, conductor 66, to binding post 42, thence by conductor 6| to the terminal 31 of the transformer, through the transformer, out through terminal 38, thence by conductor 62 to binding post 49 of the ground, thus energizing the ignition transformer and maintaining it energized as long as the ignition circuit is closed through the stack relay 4B.

Whenever the thermostat is actuated, by thermal conditions in the room or space where it is situated, to cut oif the heat, then by means of the internal workings of the stack relay connections between the contacts 51, 63 and 65 of the stack relay are broken thus de-energizing the transformer circuit, the motor circuit and the circuit through the mercury switch 13. The circuit controlled by the mercury switch, being open, the solenoid becomes de-energized and will remain de-energizecl until the stack relay 40 again calls for heat and the temperature of the oil surrounding the preheater is raised to ignition value whereupon the bimetal thermostatic member will again function to close the solenoid energizing circuit, the closing of which readies the motor circuit whenever the thermostat calls for heat. Opening of the solenoid or relay circuit will let the lever 12 pivot to the position shown in Figure 3, thus opening circuit through the mercury switch.

It will be observed that because of the provision of the solenoid holding circuit, opening and closing of the preheater circuit will have no eifect on the operation of the oil burner; the preheater circuit may open and close from time to time to maintain the temperature of the oil within the crank case at approximately that of the ignition value of the oil.

When the heat is off, caused by actuation of the stack rela 4!], and the main line is in circuit with the supply, the preheater circuit will function to maintain the oil in the crank case at the approximate ignition value of the oil for as long a time as the heat is off, so as to have ready oil at ignition value to become ignited whenever the thermostat calls for heat.

The screw 24 in the crank 28 may be moved endwise to vary the distance between its head 24a and the pin l4 of the micro switch S. The head 24a is provided with a series of holes 8| in its periphery whereby a tool, such as a pin or wire, ma be inserted to turn the screw. By turning the screw to move it towards the pin l4, temperature is lowered and by turning it to move it away from the pin l4 the temperature is raised. That is to say, as the screw 24 is moved away from the pin [4 of the switch S the lever l8 will have to be swung by the bimetal member a greater distance to cause opening of the preheater circuit thereby requiring a greater temperature to swing the bimetal element a greater amount. When the screw is moved nearer the pin M a shorter amplitude of swing of the lever 18 and crank 20 will suffice to open the preheater circuit. Thus the preheater circuit may be opened at any maximum temperature created by the heater, within the limits of the capabilities of the heater.

The head of oil is maintained in the crank case by means of a float valve (not shown) which regulates the amount of oil delivered to the crank case whenever the burner is in operation. The head of oil is such as to submerge the preheater P and the bimetal element.

Degrees F.

16 grav 120 18 do 110 20 do 100 22 do 95 The stack relay 4!] may be of any commercial type and is wired in accordance with standards employed for such instruments.

Instead of using the solenoid and mercury switch, a suitable relay could be employed to accomplish the same purpose. A room thermostat 82 is connected by a low voltage circuit 83 to contacts 84 and 85 of the stack relay ill to operate the burner when the room temperature falls to the low point of the thermostat setting.

It will, of course, be understood that various details of construction may be varied through a wide range without departing from the principles of this invention and it is, therefore, not the purpose to limit the patent granted hereon otherwise than necessitated by the scope of the appended claims.

I claim as my invention:

1. In an apparatus for heating liquids, comprising means for containing a liquid to be heated, an immersion type heater within said first means for heating a contained liquid, a bimetal member within said first means having one end fixed to said heating means and wrapped in surface contact with a portion of the periphery of the same and with the other end free, the construction of said member being such that its free end moves in one direction as the liquid. temperature rises and in the opposite direction as the liquid temperature drops, the surface engagement of the bimetal member with the heater causing movement of the free end thereof responsively to the temperature of the heater to thereby insure close control of the temperature of the liquid being heated, and means operable by movement of the free end of said member in said one direction to disable the heating means when the liquid temperature reaches a predetermined value and to maintain said means disabled until the liquid temperature drops to another predetermined value, the engagement of said bimetal member with said last mentioned means occurring Within the liquid whereby the liquid serves as a lubricant for said engaging parts.

2. In an oil burner, an oil container, an immersion type resistance heater within said container, said heater having a casing, a bimetal member encircling a part of said casing and having a free end, a rocker arm through the wall of said container having a lever depending therefrom within the container and disposed with its lower end immersed and in the path of swing of the free end of said bimetal member; said heater, said bimetal member and the lower end of said lever being immersed in the liquid within said container; an electrical circuit for said heater including a switch, a movable contact finger in said switch normally constrained to hold the heater circuit closed, said switch including an arm outwardly of said wall and connected to the rocker arm and movable to shift said finger from one circuit closing position to another circuit closing position as the lever is swung by said member, and threaded means on said arm for limiting the swinging movement thereof, the construction being such that increase in temperature of the heater causes the free end of said bimetal member to swing in one direction against said lever to swing it and rock said arm to actuate said finger to move it to another circuit closing position.

CHARLES L. RAYFIELD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,766,133 Lanser June 24, 1930 1,862,690 Macrae 'et a1 June 14, 1932 1,930,551 Blashfield Oct. 17, 1933 2,115,518 Clark Apr. 26, 1938 2,222,124 Sherman Nov. 19, 1940 2,230,732 Tapp et al. Feb. 4, 1941 2,263,833 Aldrich Nov. 25, 1941 2,27 5,689 Sheppard et a1 Mar. 10, 1942 2,310,044 Stevenson Feb. 2, 1943 FOREIGN PATENTS Number Eountry Date 618,650 Germany 1 Sept. 12, 1935 

